Java Interview @ RBS

Hi Friends,
In this post, I'm sharing interview questions asked in R.B.S.

You can also read my other Interview posts:

• Java Interview @ SAP
• Java Interview @ GalaxE
• Java Interview @ OrangeMantra
• Java Interview @ Concirrus
• Java Interview @ NexGen Solutions
• Java Interview @ Capgemini

There were total 10 questions asked in R.B.S.:


Question 1:

What is the difference between PUT and POST? Which request you will use to recharge a mobile phone?

Answer:

PUT vs POST:

• PUT is used for update operation. While POST is mainly used for Create operation.

• PUT is idempotent. So if we retry a request multiple times, that should be equivalent to single request modification.  While POST is not idempotent. So, if we retry a request N times , you will end up having N resources with N different URI's created on server. 

Generally, in practice, always use PUT for Update operations  and always use POST for create operations.


We will use POST request to recharge a mobile , because we need to create an entry for that mobile number on the server side. And we know, for creation purpose, we use POST.



Question 2:

Difference between Collections API and Stream API.

Answer:

Collection API was introduced in Java 5. While Stream API was introduced in Java 8.
Collection API is used to persist the elements. While Stream API doesn't persist the elements. It just performs operations on elements.

In Collection API, Iterator is used to iterate the collection elements. While in Streams , Spliterator is used to iterate over elements.




Question 3:

Is Stream API faster than collection?

Answer:

Yes, if we are using parallel streams, then performance of streams is better than collections.
As parallel streams use multi cores available in today's hardware, and it uses Fork Join pool and gives better performance.



Question 4:

What are the changes in Collections API in Java 8?

Answer:

Java 8 has made various changes in Collection API:

• Sorting map directly with Comparators

• Iterate over Map easily with forEach.

• Get rid of if-else condition, use getOrDefault method

• Replace and Remove utilities

• Operate directly on values

• Merge maps with merge method

• Performance improvement in HashMap, LinkedHashMap, ConcurrentHashMap

Question 5:

Have you used JProfiler? How does it works and why you will use it?

Answer:

Yes, I have used JProfiler. It is a code profiling tool.
We have to install it and then integrate with any IDE, Eclipse or IntelliJ.

It provides all the information we need with proper views and filters.
It displays the information while the program is running.

It is used to analyze performance bottlenecks like memory leaks, CPU load etc. and is also used to resolve threading issues.  

In Eclipse, we use the Profile command to profile the code using JProfiler.
JProfiler is very easy to use and finds problems in the code.


Question 6:

What are Microservices?

Answer:

The main principle behind microservices is to break a single large monolithic system into multiple independent components/processes.

 Microservices architecture allows decoupled components to be built and deployed independently to integrate into a single larger system.

These components interact with each other through a standard XML/JSON interface, irrespective of the technologies used to create the component.




Question 7:

What is REST API?

Answer:

REST stands for Representational State Transfer
REST is an architectural style for designing networked applications and developing web services.
REST API uses HTTP protocol methods/verbs for all it's operations.

It resolves around resources where every component is a resource which can be accessed by a common interface using HTTP methods.


Question 8:

Have you worked with Spring Boot? Which version?

Answer:

Yes, I've worked with Spring Boot. And version used is Spring Boot 2.



Question 9:

What are the features added in Java 8?

Answer:

Below are all the features added in java 8:

• Functional interfaces, Lambda Expressions

• New Date and Time API

• Streams

• default methods in Interfaces

• static methods in interfaces

• Collection API improvements

• forEach() method in Iterable interface.

Question 10:

What are Stream Lifecycle methods?


Answer:

Stream lifecycle is divided into three types of operations:

• Stream Source : Array, Collection, IO Channel
• Intermediate operations:  filter, sort, map, flatMap
• Operation result: List, count, sum

That's all friends.

Hope this post help everybody in clearing java/android interviews.

Thanks for reading.